Complete movie collections - Harry Potter

I purchased two of the Harry Potter movies on iTunes and own the rest on DVD, but now that my computer no longer has a DVD drive I wanted to buy them all. I purchased each individual movie for $14.99 and now see the complete set it $59.99 I was wondering if there’s any discount you can get if you already bought some? I know with tv seasons if you’ve bought an episode or two you can complete the season for a cheaper price. Is this the same with complete movie series? I’d hope so, but not seeing it.